It provides a new imaging technology for the diagnosis of liver cancer. Positron Emission Computed Tomography (PET-CT) is a functional molecular imaging system that integrates PET and CT into one, which can reflect the biochemical and metabolic information of liver occupying tissues by PET functional imaging and precisely locate the lesion by CT morphological imaging, and at the same time, whole-body scanning can understand the overall condition and assess the metastasis to achieve the purpose of early detection of the lesion. The creation of PET is a new milestone in the development of nuclear medicine, and it is highly sensitive and can be precisely localized compared to SPECT. The radionuclides used in PET, such as 11C, 15O, 13N and 18F, are important components of human tissues, and the most widely used metabolite and marker is fluorodeoxyglucose (18F-FDG). in the tissue cells, showing high concentration and being examined by the instrument. The high expression of glucose transporter on the tumor cell membrane and the enhanced expression and activity of intracellular hexokinase showed the high concentration of 18F-FDG in tumor tissues, and the standard uptake value was significantly increased in PET examination. The sensitivity of PET for hepatocellular carcinoma ranges from 50% to 70%, but its specificity can be as high as 90% for benign intrahepatic occupying lesions. These isotopically labeled compounds do not alter the metabolic properties of living macromolecules, and the very short half-lives of these radionuclides allow for the use of larger doses to obtain high quality images while still receiving low radiation doses, which also facilitates repeated imaging and accurate “tracer” studies. However, PET is expensive and the nuclides used need to be generated by gas pedals, so it is not yet commonly used. Xiaofeng Liu, Department of Gastroenterology, General Hospital of Jinan Military Region